Tumor hypoxia plays an important role in the malignant progression and clinical outcome of solid cancers. This may be because tumor hypoxia induces the expression of angiogenic and cell survival-promoting cytokines and enhances invasiveness of cancer cells. We have recently provided evidence for hypoxia-inducible autocrine erythropoietin (Epo) signaling in the malignant progression of several human cancers including breast, cervical, endometrial, and head/neck cancer. Epo and the Epo receptor (EpoR), are among many genes upregulated by tumor hypoxia, and Epo signaling promotes invasiveness of head/neck cancer cells. The transcription factor known as hypoxia-inducible factor-1 (HIF-1) is critically involved in tumor hypoxia induced adaptations. Expression of HIF-1 alpha, the key hypoxia-regulated subunit of HIF-1, is highly up-regulated in a variety of human cancers and is strongly correlated with tumor grade, angiogenesis, and adverse clinical outcome. We have discovered a novel hypoxia-independent mechanism that increases HIF-1 alpha levels in cancer cells via the glycolytic metabolite pyruvate. We have also discovered that ascorbate and specific amino acids can reverse this process. The goal of this application is to determine whether lowering basal HIF-1 expression by using ascorbate and amino acids can reduce HIF-induced gene expression, Epo signaling, and invasiveness of human head/neck cancer cells. We will also determine whether in vivo treatment with ascorbate and amino acids can lower HIF-1 expression, Epo and EpoR expression, and tumor growth in a human head/neck cancer xenograft model. We believe that our studies will yield novel and safe therapeutic options for cancer patients. [unreadable] [unreadable]